Everything works find if ajaxSingle is set to false, but by setting it to "true", the actionListener method (actionDummy) is not called.

I traced the code of JSF and A4J and it seems that in cases that ajaxSingle=true, in AjaxViewRoot.processPhase line 246 which calls invokeOnComponent, no equal component is found, so actionEvent is not queued and hence the actionListener is not called.